Cu₂Te is commonly used as the backside contact of CdTe-based solar cells. We predict a stable topological semimetal structure of Cu₂Te(R3m) with triply degenerate nodal points near the Fermi energy. Triply degenerate nodal points are formed by the band crossing between two states with angular momentum j equal to 3/2 and 1/2 along the unique C₃ axis. The anisotropic strain breaking C₃ symmetry opens the energy gap, and transforms semimetal Cu₂Te(R3m) into a topological insulator. It provides strong evidence for understanding the unconventional large linear magnetoresistance in Cu_2−xTe. The band crossing of Cu₂Te(R3m) strongly depends on the orbital on-site energy difference and the SOC strength. Crystal structures with the space group R3m (no. 160) are a good platform to obtain topological semimetals with triply degenerate nodal points. Compounds X₂Y (X = Cu, Ag, Au, Y = O, S, Se, Te) except for Au₂S and Cu₂O are topological semimetals with triply degenerate nodal points around the Fermi energy.

中文翻译：

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稳定的Cu2Te结构中具有三重简并节点的拓扑半金属态

Cu ₂ Te通常用作基于CdTe的太阳能电池的背面触点。我们预测一个稳定的拓扑半金属结构的Cu ₂ Te（R 3 m）在费米能量附近具有三重简并的结点。由沿唯一C ₃轴的角动量j等于3/2和1/2的两个状态之间的能带交叉形成了三个简并的结点。打破C ₃对称性的各向异性应变打开了能隙，并转变了半金属Cu ₂ Te（R 3 m）成拓扑绝缘体。它为理解Cu _{2- x} Te中的非常规大线性磁阻提供了有力的证据。Cu ₂ Te（R 3 m）的能带穿越在很大程度上取决于轨道的现场能量差和SOC强度。具有R 3 m空间群（第160号）的晶体结构是获得具有三重简并节点的拓扑半金属的良好平台。除Au ₂ S和Cu ₂ O外，化合物X ₂ Y（X = Cu，Ag，Au，Y = O，S，Se，Te）是拓扑半金属，在费米能附近具有三重简并的结点。